In certain excavating operations where the material being excavated consists of coarse and fine aggregates such as rocks and soil, it often is desired to extract only the coarser aggregate which requires sifting the coarse aggregate from the fine aggregate. Such sifting may be accomplished by excavating both the coarse and the fine aggregate at an excavating site, transporting such excavated aggregate to another work site equipped with a sifting apparatus and then processing such material in such apparatus to accomplish the desired sifting. A more efficient manner of accomplishing such a sifting is to provide for means on the excavating equipment to perform the sifting during the excavating operation. Examples of such means are illustrated and described in U.S. Pat. Nos. 3,003,265 to Lutzens, 3,765,490 to Logue, 4,805,703 to Carlson, 4,858,346 to Shule, 5,160,034 to Potter, 5,172,498 to Wack and 5,528,844 to Ellis.
Prior part devices mountable on excavating machines for sifting aggregate at excavating sites have been found not to be entirely satisfactory in terms of simplicity of design, ease of manufacture and/or performance in service. Accordingly, it is the principal object of the present invention to provide an improved assembly mountable on a ground working or material handling machine for sifting material at work sites which is simple in design, easy to manufacture and maintain, simple to operate and effective in performance.